A new coherent optical pseudo-color encoder

A new and simple method for pseudo-coloring a photograph in a coherent optical processing system, utilizing a newly developed technique of half-tone screens, is described. By selective spatial filtering of the high diffraction orders in the Fourier plane of a coherent optical system, images with up to ten contours of constant brightness have been generated on a picture from a single half-tone copy of that picture. The pseudo-coloring of the picture is achieved by mixing the high-diffraction-order outputs generated by lasers of different wavelengths. In the experiment described herein, an argon laser and a He-Ne laser were used. The experimental results demonstrate that the method has considerable flexibility. A discussion of the theory, the method, and potential applications is given.